So reading online it seems river red gum is a 3-15c tree. 37-104f. We get freezes here a few times in the winter and summers are well over 104 for long periods. All summer…
Water might also be an issue. Pretty dry here and they probably mostly depend on irrigation canals which can be on or off for whatever reason. Then this winter we got a lot of rain and wind, hence the toppling scrapers.
A couple years ago I removed some smaller eucs that beetles got but I haven’t seen them since. They were drought stressed.